Numerical Models for Scour and Liquefaction Around Object Under Currents and Waves

166 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008.For the liquefaction process, two different mechanisms (momentary and residual) are considered. For momentary liquefaction, a three-dimensional numerical model for the sea bed response under free surface water waves is constructed. Free water surface is modeled by volume of fluid (VOF) method and water waves are generated by numerical wave-maker boundary condition. An iterative numerical scheme is proposed to solve the Biot consolidation equation using a finite volume method (FVM). The coupling between water wave and sea bed is through both pressure and stress conditions on common boundaries. For residual liquefaction, the solutions to the one-dimensional model equation of the period-averaged pore pressure buildup are listed. The accumulation of pore pressure is modeled as the effect of the source term in the storage equation. Corrections to the solutions in the literature are provided. For deep soil condition, an asymptotic solution is proposed to estimate the pore pressure. A numerical model is also developed to solve the one-dimensional period-averaged pore pressure buildup equation. Good agreement between the results of numerical model and analytical model are found. These results also agree with the experiment data. A tentative step is also made to model the phase-resolved pore pressure. The basic idea of adding a source term to the governing equation is explored. The source term has the same form as that of the period-averaged residual pore pressure model. Test case shows that this model gives good results comparing to the one-dimensional period-averaged model.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD